The Phase I feasibility study has successfully demonstrated that significant performance improvement can be achieved using the Electrospray Ion Source (ESPI) with a rotary pumping stage between the atmospheric pressure Electrospray chamber and the mass spectrometer source chamber. The ESPI source performance increase was compared to the previous design at Yale University having no rotary pumping stage. In the proposed Phase II research and development plan many of the preliminary ESPI performance studies begun during Phase I will be explored in more depth. The primary research goals of the Phase II effort are to improve the overall sensitivity over a broader range of solutions, characterize the ion beam energy and energy spread, determine the collisional induced effects in the region between the capillary and the skimmer, improve the multiply charged spectra deconvolution algorithms and begin developing deconvolution algorithms applied to the NO/NU daughter spectra of multiply charged parents. Results of this research will be used to improve the design of the ESPI source, support module and of software program products. The installation of a triple quadrupole mass spectrometer system at Analytica of Branford is requested under Phase II funding to conduct a efficient in-house research program with the Electrospray Ion Source.